Highly efficient bioconversion of methane to methanol using a novel type I Methylomonas sp DH-1 newly isolated from brewery waste sludge

BACKGROUND: Methane is the major component of natural and shale gas. Methane can be converted into methanol via a bioprocess using methanotrophs, and methanol is a valuable chemical feedstock for the production of value-added chemicals. This work demonstrates highly effective bioconversion of methane to methanol using a newly isolated novel methanotroph, Methylomonas sp. DH-1. RESULTS: A novel methanotroph strain was isolated from activated sludge from a brewery plant and characterized using phylogenetic analysis, electron microscopy and chemotaxonomic analysis. This aerobic, Gram-negative, non-motile rod-shaped type I methanotroph was designated as Methylomonas sp. DH-1. The growth condition of Methylomonas sp. DH-1 and batch methane-to-methanol bioconversion conditions such as methane concentration, pH, biocatalyst loading, concentration of formate and MDH inhibitor were analyzed and optimized. Methanol was produced from methane with a 1.340 g L-1 titer, a 0.332 g L-1 h(-1) volumetric conversion rate and a 0.0752 g g(-1) cell h(-1) specific methanol conversion rate. CONCLUSION: It was demonstrated that isolation and application of a new methanotroph strain is a practical way of improving bioconversion efficiency in the conversion of methane to methanol. Moreover, one promising feature of Methylomonas sp. DH-1 for methanol production was its extremely high tolerance to methanol up to 7%(v/v), which is advantageous for high-titer methanol production. (C) 2016 Society of Chemical Industry